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SPICE modelling of PFC
controller
Krzysztof Górecki, Janusz Zarębski
Department of Marine Electronics
Gdynia Maritime University, POLAND
T
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Outline
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Introduction
Structure and principle of operation of the
device UC3853
Model of the device UC3853
Results
Conclusions
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Introduction (1)
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Switched mode power supplies commonly used in
electronic installations cause changes for worse of the
quality of energy in the line.
This phenomenon results from the fact that switched mode
power supplies absorb a current from the line in the pulses
form.
Power supplies can be treated as the nonlinear RLC load of
the line and the power consumed by switched mode power
supplies comprises: active and reactive powers.
The second quality of energy influences disadvantageously
the operation of many installations connected to the power
network, e.g. electrical machines, causing an additional
increment of their winding temperature.
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Introduction (2)
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The important parameter characterizing the electrical
installation influencing the electrical energy quality is the
power factor (PF).
To obtain a high value of PF, a switched mode power
supply input current should be formed in such a way as
to get the sinusoidal course of current synchronized with
the course of the line voltage.
To get the proper shape of the input current, special
circuits of power factor correction (PFC) are used.
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Introduction (3)
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Currently, the predominant role is played by active PFC
consisting of dc-dc converters and special integrated
circuits working as a PFC controller.
Today, a lot of concerns offer such circuits, that realize
different algorithms of power factor corrections.
Designing and analysing electronic circuits demand the
use of credible models of circuit elements, acceptable by
the proper software, e.g. SPICE.
There is no information about the models of PFC
controllers for SPICE.
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In the paper
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In this paper the authors present a new model of a PFC
controller realizing the control of the average value of
current.
For the considerations the device UC3853 (Texas
Instruments) has been chosen.
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Structure and principle of operation of
the device UC3853
IAC
IMO
ICOMP
REF
VCC
7.05 V/7 V
VCOMP
EA
MULT
FB
CA
COMP
FF
R Q
X2
3V
OVP
3.9 kW
VCC/8
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OS
OUT
S
15 V
GND
3.15 V/3 V
SYNC
11.5 V/9.5 V
SYNC
OSC
The considered device consists of nine blocks enabling the control
of the average value of the input current and the output voltage
as well as two protection blocks.
The control of the current and voltage is realized by the error
amplifier (EA), the multiplier (MULT), the squaring circuit (X2), the
current amplifier (CA), the PWM comparator (COMP), the oscillator
(OSC), the RS flip-flop (FF) and the output stage (OS). The device
also includes the blocks protecting the overvoltage at the device
output and too low value of the supply voltage.
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Model of the device UC3853
Vcomp
IMO
IAC
ICOMP
60
Riac
G1
4
Rwp
Gmn
R1
icomp1
1
E_pwm
VCC
FB
E_ovp
ovp
50
E_wp
21
E_kw
R2
2
Vosc
Rout
E_inwr
3
Vosc1
7
E_inw
OUT
8
E_and
•The model of the device UC3853 has developed according to the principles of
formulating integrated circuits models for SPICE and the catalogue data.
•The presented model consists of 2 controlled current sources, 6 controlled
voltage sources, 2 independent voltage sources, 5 resistors and 2 NAND gates.
•The detailed description of the sources efficiency – see proceedings
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Results (1)
The tested switched-mode power supply containing the controller UC3853
DBP
Iin
L
DD01
DD02
LF
CF
Vin
DD03
N2
CIN
RAC1
RM0
IAC
RCZ
7 VCOMP
RVC
8 FB
CVC
CVCZ
UC 3853
6 IMO
CCZ
Q
C0
Vout
R0
RB1
RVI1
RAC2
5 ICOMP
DFF
RS
DD04
CCP
DOUT
RQ
RB2
1
VCC
2
OUT
3
GND
4
RVI2
DQ
DM0
CFF2
CFF1
RVD2
RVD1
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Results (2)
Vin = 150 V
3
450
400
1
350
-1
Iin [A]
Vout [V]
300
250
200
-3
-5
150
100
-7
50
-9
0
0
0,04
0,08
0,12
t [s]
0,16
0,2
0
0,04
0,08
0,12
0,16
0,2
t [s]
•The nominal value of Vout is 130 ms after switching on this device
•The input current is sinusoidal, but its amplitude is changing with time. In the
steady state, this amplitude slightly exceeds 1 A
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Results (3)
Vin = 310 V
2
400
0
350
-2
300
-4
Iin [A]
Vout [V]
450
250
200
150
-6
-8
-10
-12
100
-14
50
-16
0
0
0,04
0,08
0,12
t [s]
0,16
0,2
0,24
-18
0
0,04
0,08
0,12
0,16
0,2
0,24
t [s]
•The results of switching-on the overvoltage protection circuit at the beginning of
the power supply operation is shown.
•Not before reaching 110 ms, the power supply input current is of the desirable
sinusoidal form.
•In the steady state the measured characteristics are qualitatively similar to the
calculated ones
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Conclusions
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In the paper the new SPICE model of the monolithic PFC controller
UC3853 is proposed.
The results of the analysis of the power supply with this PFC device,
confirm the correctness of the model.
The presented results of the analysis confirm the proper description of
all the blocks of the device responsible for regulation of the output
voltage and the input current of the device as well as the overvoltage
protection circuit.
The model can be useful for designers of power supply systems,
especially such systems with the PFC circuit.
In spite of the fact that the model was investigated for the device
UC3853 only, it can be used for other PFC controllers based on the
conception of controlling the current average value.
The drawback of the model is long time of an analysis to get the
steady state, which can reaches even a few hours
In further investigations the authors will elaborate a special algorithm,
which will enable shorting the analysis of the considered class of the
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power supply systems.